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Digitale Medien

Storage of the phytochrome-mediated phototropic stimulus of moss protonemal tip cells (1988)

Hartmann, E. ; Weber, M.

Springer

Planta 175 (1988), S. 39-49

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ISSN: 1432-2048

Schlagwort(e): Calcium (chlorotetrcycline fluorescence) ; Ceratodon ; Monensin ; Phototropism (moss) ; Phytochrome (moss) ; Protonema (moss) ; Tip growth (moss protonema)

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Abstract A phytochrome-regulated phototropic response of the moss Ceratodon purpureus was investigated. Chlorotetracycline (CTC) was used to visualize membrane-associated calcium gradients in the tip cell of moss caulonemal filaments. A tip-to-base Ca2+ gradient was observed. The ionophore monensin rapidly inhibited the growth of the tip cell and abolished the CTC fluorescence. Six hours after transferring to inhibitor-free medium, protonemal growth resumed and reached the normal growth rate within 12 h. The growth was accompanied by a reappearance of the CTC-fluorescence gradient. Unilateral irradiation given during the monensin treatment or after the treatment during the period when growth inhibition persisted led, with the re-initiation of growth, to a typical positive phototropic bending in complete darkness. Far-red light applied just before the growth response started, or during growth inhibition, abolished the phototropic response. The phytochrome-mediated signal was qualitatively (position) and quantitatively (degree of bending) memorized. Signal perception and response could be separated temporally. This result indicates that at least under some circumstances, e.g. under the influence of monensin, the phytochrome-mediated signal can be stored for several hours in darkness. Calcium seems to be essential for the processing of polar growth only. A specific function (second messenger) in phytochrome-dependent signal transduction could not be confirmed.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00402880

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Digitale Medien

Untersuchungen an oxidischen Katalysatoren. XLIV. Beeinflussung des katalytischen Verhaltens modifizierter Zeolithe vom Typ ZSM-5 durch thermische BehandlungProfessor Wolfgang Wieker zum 60. Geburtstage am 19. April 1987 gewidmet (1987)

Wendlandt, K.-P. ; Reschetilowski, W. ; Unger, B. ; [weitere]

Weinheim : Wiley-Blackwell

Zeitschrift für anorganische Chemie 547 (1987), S. 142-148

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ISSN: 0044-2313

Schlagwort(e): Chemistry ; Inorganic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Beschreibung / Inhaltsverzeichnis: Studies on Oxide Catalysts. XLIV. Modification of the Catalytic Behavior of Modified ZSM-5 Zeolites by Thermal TreatmentThe catalytic activity, the shape selectivity, and the deactivation behavior of ZSM-5 in paraffin cracking reactions can be regulated by a thermal pretreatment. A minimum of the deactivation rate as a function of zeolite pretreatment time at 600°C found in the hexane cracking could be verified in the methanol conversion reaction to gasoline.

Notizen: Die katalytische Aktivität, die Formselektivität und das Aktivität-Zeit-Verhalten des ZSM-5 beim Spalten von Paraffinen kann durch thermische Vorbehandlung stark beeinflußt werden. Ein in der Spaltung von Hexan gefundenes Minimum der Desaktivierungsgeschwindigkeit als Funktion der Dauer der Vorbehandlung bei 600°C konnte in der Methanolumwandlung zu Benzin verifiziert werden.

Zusätzliches Material: 4 Ill.